Last



June 15 1926.

E. SIEBERT NE RFRICH El AL LAST Filed Feb. 11, 1925 Patented June 15, 1926.

' UNITE STATES APATENT FFICQE.'

EMMA SIEBERT, NE. RPRICH, MARTHASIEBERT, AND ALBERT SIEBERT, OF MAGDE- BURG, GERMANY. i

LAST.

Application ied February 11, 1825, Serial No. 8,569, and in Germany February 20, 1924.

, Boots made on the commonly used lasts have the inconvenience thatv they are tread down on the outer side as the `toot has the tendency to inove beyond the edge of the sole. As the foot is held at the rear by the stiff heel Acap this treading down proves that the shape of the last is not correct. In a boot which has been used some time the c entre line of the sole of the foot does generally no longer vcoincide rwith the centre line of the sole of the last, wherefr'om results a regular wearing of the boot sole and of the heel.

It has been proposed to avoid this by giving to the last a special shape so that the centre line ot the last in the rear part 'forms an angle with the centre line of the forepart. In the lasts of known type the point or" intersection between the centre line 'of the rear part and the centre line of the torepart is wrongly situated, e. g. too far advanced, in proximity of the ball. The angle between the two centre lines is further sometimes too acute.

The present invention is based on the knowledge that the point of intersection of the centre line of the rear part of the last and ot the centre line of the tore-part of the last must be situated in the last third at the rear of the last and the angle formed by the two centre lines must be of about 10. It is further important that the cross section of the rear part ot the last be different trom the commonly used cross section in order to more uniformly distribute the mass of the wood at either side of the centre line.

On the accompanying drawing v Figs. 1 and 2 illustrate the theoretical principle for the selection ot this point of intersection with vthe aid of the bony structure ot a ioot shown in plan view.

Fig. 3 is a cross section through the rear part of the last on line ct-a of Fig. 4f, the center line of the commonly used shape of the last being shown in dash line and the shape of the last improved according to the invention being shown in full lines.

Fig. 4 is a plan view ot the last sole according to this invention.

Fig. 5 shows a plan of a last built over this fundamental form and the last wedge.

The actually used theory considers the bony structure ot the foot as an arch which bears on the ground at the heel and at the ball, it being supposed that the toot moves along a line which connects approximately the centre oi' the big toe with the centre ot the heel. This Walking line moveover forms the basis of the theoretical construction of boots. The action of the bony structure oft the ootis however in reality not so simple as the foot executes lever-like actions.

. The one or" these levers is indicated in Fig. l and the other in Fig. 2.

The tibia rests upon the talus l at the side which is in Fig. l at the right. The talus is supported by the scapha 2, the three` wedge-bones 3 and the three metacarpal bones 4 oi' the halt` of the foot situated on the inner side. On the three metacarpal bones follow the three toes the bones ot which do however intervene very little to support the weight of the body. The three wedge bones 3 and the three inetacarpal bones 4 form a transverse arch which is supported by the second lever (Fig. 2).

This second lever which forms a` longitudinal arch is composed ot the heel bone 5, the cuboid bone 6 and the two outer metacarpal bones i' on which follow again the toes. The talus l rests, as can be 4seen from Fig. 2, upon the heel bone. The rear part ot the heel bone bears upon the sole and carri-es the talus. The outer lever (Fig. 2) prevents in this manner the giving way oi' the arched inner lever (Fig. l). In order to enable this propping the outer lever must be pressed against the inner lever and sit upon the ground as straight as possible. The shape of the rear p-art oit the boot must appronimately correspond with the position and formation of the heel bone in order to give the correct support. This means that the rear part of the last must stand, with regard to the orepart, at an angie ot approximately 10 and the apex ot this yangle must be a point which is situated above the talus. The angle must be outwardiy directed.

Hereiirom results the fundamental shape of the sole of the last shown in Fig. li. The iront centre line 9 of sole 8, said line having been obtained by bisecting the cross lines, is outwardly inclined so that at the point M the centre line 10 of the rear part of the last and the prolongation ot the centre line 9, enclose an angle of .approximately 10. On the inner side of the boot an outward bulging ll and on the outer side @if @he sans a beloven 12 are formed. which must remain visible when the last is being niade.

Fig. 5 shows the last 13 built over this fundamental shape and the-last wedge lf-i.

In Fig. 5 the Centre line 9 forins with the centreiline l0 of the rear part an angle of 10. The two Centre lines intersect at the point m above the talus. This point m is situated approxin'iately at the beginning of the last third of the length of the last, counted from the toes.

The cross section of the last must also be somewhat diiierent from the commonly used cross section. The cross section has hitherto, as shown in Fig. 3 in dash line, been convex at the inner side and concave at the outer side so that the greater portion of the inass of the wood is on the inner side oi the centre line 10. In ord-er to obtain a position of the heel resembling the foot position the Wood must however be uniformly distributed at either side of the centre line, as shown in Fig. 3 in full line. On the inner side inust be a cavity and on the outer side a bulged out part, which is just eontrar)T to the shape of the commonly used lasts.

le claim l. A last for boots in which the rear part stands in outward direction at an angle to the fore-part having the centre line ot the rear part located so that it fornis with the Centre line of the fore-part an angle of approxiniately 100 and so that it intersects this centre line ot' the lore-part .at a point which is situated approximately at the beginning oi: the last third of the length of the last Counted :troni the toes.

A last -for boots having its heel so shaped that the niass oi' the wood is uniformly distributed at either side ot the centre line, the inner side of the heel part being concave and the outer side being con- Vex.

In testimony whereof We allix lour signatures.

EMMA SIEBERT, RFRICH. liiART-IA IEBER-T. ALBERT SEBERT. 

